Space Exploration Technologies — better known as SpaceX — is planning to launch its Dragon capsule toward the orbiting lab on Nov. 30, with a historic docking slated for nine days later. But as a result of the Aug. 24 crash of the unmanned Russian Progress 44 supply ship, there might not be any astronauts aboard the station to receive Dragon in early December.

If that's the case, Dragon's launch would have to be postponed.

An artist's interpretation of a SpaceX Dragon cargo ship docked at the International Space Station CREDIT: SpaceX/NASA

If Dragon's second demonstration mission is a success, fully operational re-supply missions with the capsule could begin as early as three or four months later, SpaceX officials have said.

NASA and SpaceX might still hit their original timelines. The Russians appear to making progress on their investigation of the Soyuz anomaly, Suffredini said.

"Right now, I think they would tell you they're cautiously optimistic that they'll keep the ISS manned at least to three crew," Suffredini said. Doing so, he added, would mean "you were able to fly at least one Soyuz between now and the middle of November."